Apparatus for adding liquid to a liquid flow system

ABSTRACT

Apparatus for automatically adding a liquid to a liquid flow system to maintain the proper quantity and composition of the liquid in the liquid flow system. The liquid is added to the flow system by means of a valve which senses the quantity of liquid in the flow system and actuates a fluid circuit to automatically provide the necessary quantity of liquid to be added.

United States Patent inventor App]. No.

Filed Patented Assignee APPARATUS FOR ADDI NG LIQUID TO A LIQUID FLOW SYSTEM 12 Claims, 1 Drawing Fig.

U.S. Cl 137/263, 137/563 Int. Cl E03b 7/07, E03j 1 1/00 Henry G. Joel New York, N.Y.

Dec. 11, 1969 Dec. 14, 1971 lug. C. Olivetti & C.S.p.A

lvrea, Italy [50] Field of Search 137/563, 263, l 13, 1 14 [56] References Cited UNITED STATES PATENTS 2,690,764 10/1954 Hoffmann 137/563 Primary Examiner-Henry T. Klinksiek Atlorney- Kevin McMahon ABSTRACT: Apparatus for automatically adding a liquid to a liquid flow system to maintain the proper quantity and composition of the liquid in the liquid flow system. The liquid is added to the flow system by means of a valve which senses the quantity of liquid in the flow system and actuates a fluid circuit to automatically provide the necessary quantity of liquid to be added.

PATENIEB 05:14:91:

INVENTOR HENRY G.JOEL BY firm Mm ATTORNEY APPARATUS FOR ADDING LIQUID TO A LIQUID FLOW SYSTEM BACKGROUND OF THE INVENTION Field of the INVENTION This invention relates to liquid flow systems adaptable for use in processing apparatus and more specifically to a liquid flow system for recirculation of an ingredient in processing apparatus.

Description of the Prior Art It has long been a problem to maintain proper and uniform conditions in processing apparatus which recirculate a working liquid. Typical working liquids recirculated in processing apparatus usually include an active ingredient suspended or dissolved in a carrying liquid. As the process operates, the active ingredient is consumed by the process and the carrying liquid is depleted by evaporation, leaks in the system, or ab sorption in the material processed.

In order to maintain the proper quantity and unifonnity of the working liquid in the flow system, it is necessary to replenish both the volume of the carrying liquid which has been depleted and the quantity of the active ingredients which have been consumed in the operation of the process.

These problems associated with working liquids have been particularly pronounced in the electrostatic photographic copying art where an inklike working liquid referred to as a developer is used to fix the copied image on paper. The developer liquid consists of a special opaque ingredient referred to as toner and a carrying liquid referred to as thinner. The toner coacts with previously processed paper to form the image on the paper, and the thinner, which carries the toner, evaporates shortly after the developer has been applied to the paper, leaving the paper dry and with a distinct image.

A greater ratio of toner to thinner is consumed by the developing process than is present in the composition of the developer liquid. Therefore, as the developer liquid is circulated in the developing process, the concentration of toner in the developer will continually decrease, resulting finally in the nonoperativeness of the entire electrostatic photographic copying system.

Prior efl'orts to maintain the proper composition of the developer liquid have not been fully successful. Concentrated replenisher liquids were formulated which contained toner and thinner in the same or larger proportions as these materials were depleted from the developer liquid. However, the replenisher liquid had to be most carefully added to the developer liquid. If too little replenisher were added, the toner concentration would be low. If too much replenisher were added to the developer, the toner concentration would be too high. Further, it was often necessary to insure that the replenisher was added to the developer without any contamination of the replenisher by the developer, since the adding of developer to replenisher would adversely effect the properties of the replenisher liquid.

Because of the accuracy required in adding the replenisher liquid to the developer, the obvious expedient of adding a fixed quantity of replenisher at a given point in the developing process was unsuitable. Any error in the fixed quantity to be added would be continually repeated, eventually producing a large imbalance in the composition of the developer.

Apparatus used in other processing arts could not completely eliminate the problems mentioned above. For example, the apparatus shown in U.S. Pat. No. 2,235,336 issued March, 1941 to F. Schuster for Apparatus for Maintaining a Liquid in Uniform Condition could not solve all of the problems mentioned above. In the Schuster patent, a float valve 20 actuated by a float 2] permits replenisher liquid from a reservoir 17 to flow to a container of replenishing liquid 14 until the level of the working liquid in the container is sufiiciently raised.

The float valve arrangement disclosed by Schuster, however, is not very precise, nor is it responsive to minor changes in the level of the liquid. Therefore, if the Schuster apparatus were used to add replenisher to a developer, large quantities of developer would have to be circulated in the system to dilute the effect of adding improper quantities of replenisher. Additionally, the system presents certain space problems for applying it in limited areas since the reservoir 17 must be mounted above the container 14 in order to provide the head to cause the flow from the reservoir to the container when the float valve opens.

An example of an attempt to solve the above-mentioned problems in the electrostatic photographic copying art is shown in U.S. Pat. No. 3,299,787 issued to E. R. Kolb, et al. in Jan. 1967, for Electrophotographic Micro-Copy Printer. However, as can be clearly seen from FIG. 13 of this patent, an elaborate system is necessary to separately supply the required quantities of thinner from storage container 230 and toner from container 233. The toner is released from its container 233 by an electrically actuated valve 237 which is triggered by a photocell 241 when the amount of toner in the developing liquid diminishes to the point that suflicient light from light source 242 is sensed by the photocell 24].

SUMMARY OF THE INVENTION In order to overcome the problems set forth above and to meet the shortcomings of the prior art, the present invention sew forth an apparatus which can be utilized to maintain the proper quantity and unifonnity of a working liquid in a liquid flow system. The apparatus includes a simplified float actuated valve device disposed in a liquid flow system which valve device produces a pressure drop in the flow system when the quantity of working liquid becomes insufficient. The valve device automatically maintains the reduced pressure in the liquid flow system until the required quantity of liquid to be added to the working liquid is drawn into the liquid flow system.

Accordingly, it is an object of the present invention to provide apparatus for maintaining the composition of a consumable multicomponent working liquid used in the fluid flow system of processing apparatus.

Yet another object of the present invention is to provide apparatus for automatically replenishing a consumable working liquid in a liquid flow system.

Still another object of the present invention is to provide apparatus of simplified construction for automatically replenishing working liquid used in a liquid flow system.

Yet another object of the present invention is to provide apparatus for automatically replenishing the working liquid in a liquid flow system which apparatus is highly reliable and not prone to failure or malfunction.

Still another object of the present invention is to provide apparatus for maintaining a proper level of working liquid flowing in a liquid system.

A further object of the present invention is to provide apparatus for maintaining the composition of a multicomponent working fluid in a liquid flow system without having to separately add the individual components which make up the working liquid.

Still another object of the present invention is to provide apparatus for automatically adding a replenishing liquid to a working liquid in a liquid flow without the possibility of the working liquid contaminating the replenishing liquid.

Yet another object of the present invention is to provide apparatus for automatically replenishing a consumable working liquid in a liquid flow system which apparatus can be cheaply fabricated and easily fabricated from common industrial materials.

Various other objects and advantages will be apparent from the following description of the embodiment of the invention and the novel features will be particularly pointed out hereinafter in connection with the appended claims.

DESCRIPTION OF THE DRAWING The drawing depicts a liquid flow system incorporating the features of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred embodiment of the invention shown in the FIGURE is a liquid flow system adapted for use in a developing system for an electrostatic photographic copying device. A using means in the form of a processing bin generally indicated at is connected to a reservoir generally indicated at 12 by means of a return conduit 14, extending from an outlet 18 in bin 10 to an inlet 16 in reservoir 12. An outlet 20 in reservoir 12 is connected to an inlet 22 by means of a first conduit generally indicated at 24. Liquid in reservoir 12 is delivered to processing bin 10 by a pump 26 which is mounted in the first conduit means 24 and divides the conduit into a pump inlet portion 25 and a pump discharge portion 27.

A processing roller 28 is mounted in processing bin 10, and the level of liquid in the processing bin is determined by the height of the end 30 of return conduit 14 above the bottom 32 of bin 10. When the liquid level 34 rises above end 30 of return conduit 18, the liquid will flow through the return conduit into the reservoir 12. Several drain holes 36 are located in return conduit 18 near the point that the conduit passes through the bottom 32 of bin 10 to allow liquid in the bin to gradually drain into the reservoir 12 when the system is not in operation.

Reservoir 12 is fabricated from a cylindrical section 38 which is connected to a flat circular bottom 40 by a conical section 42 whose function will be explained in greater detail below. The end 44 of the first conduit means 24 extends slightly into the reservoir 12.

A spherically shaped float 46 is located in the reservoir. The float has a diameter large enough in relation to the diameter of the cylindrical section 38 to prevent the float from lodging or jamming in any area of the reservoir, but small enough in relation to the diameter of the cylindrical section 38 to allow the float to freely rise and fall with the level of liquid in the reser- VOII.

A cover 48 is placed over the top 50 of the reservoir 12 to prevent evaporation of the liquid which flows in the system when that liquid is stored in the reservoir during periods of nonoperation of the system.

When the level of the liquid in the reservoir drops from the highest level indicated at 52 past the intermediate level 54, down to the lower level 56, the float 46 will drop to the bottom of the reservoir. Depending upon the relative height of the end 44 of first conduit means 24 above the circular bottom 40 of the reservoir, and the diameter of the float 46, the float will either rest on the end 44 of the first conduit means or the conical section 42 at the bottom of the reservoir, In either event, the float 46 will effectively prevent any additional liquid in the bottom of the reservoir from entering the first conduit 24. If pump 26 is operating, the suction of the pump inlet coupled with the lack of liquid entering first conduit 24 from end 44 will produce a pressure drop in the pump inlet conduit 25 of the first conduit means 24.

A second conduit means generally indicated at 60 intersects the pump inlet conduit portion 25 of the first conduit 24 at a point 62 which is disposed intermediate the outlet 20 of reservoir 12 and the pump 26. The other end of the second conduit means 60 forms a pickup tube 64 which extends down close to the bottom 66 of a liquid container 68 holding a replenisher which is to be added to the flow system. A vent 70 is located in the top 72 of the liquid container 68 to prevent a vacuum from occurring within the container.

A portion 74 of the second conduit 60 is constricted to provide an impedance to the flow of liquid through the second conduit from the container 68 to the first conduit 24 and vice versa.

OPERATlON When the liquid flow system is at rest, the reservoir 12 will be filled to the upper level 52 with the working fluid for a processing system, in this case, developing solution for the developing process in an electrostatic photographic copying apparatus. The processing bin 10 will be empty since all of the developing liquid will have drained through drain holes 36 into return conduit 14 and then to the reservoir 12.

When the developing system is started, the pump 24 will draw the developing liquid from the reservoir through a pump inlet conduit 25 of the first conduit means 24, and pump the developer through the pump discharge conduit 27 of the first conduit 24 into the processing bin 10. Since the drain hole 36 can only carry a flow rate much smaller than the output of the pump 26, the level of the developer in the bin will rise until it reaches level 34 above the end 30 of retum conduit 14.

When the developer has reached the proper level in the processing bin, the level of the developer in the reservoir will have dropped down to level 54, and the developer will continue circulating from the reservoir to the processing bin where a paper to be treated will be passed underneath roller 28 to be immersed in the developer. The developer will then return from the processing bin back to the reservoir through return conduit.

As mentioned above, the rate at which the toner and the thinner will be consumed as the developing liquid is recycled in the developing process will be different from the proportion in which these two components are present in the developing liquid. Therefore, the replenishing solution is formulated to have toner and thinner in the same ratio that these components are consumed during the developing process.

For example, if, as is usually the case, a greater amount of toner is used than thinner, the replenishing liquid stored in liquid container 68 would have the same proportion of toner to thinner as is consumed in the developing process.

As the level of the developer in the reservoir 12 continues to drop, a float 46 will descend until it is nearly seated on either the conical section 42, or seated on the end 44 of the first conduit means. As the float approaches the seated position, it will start to restrict the flow of the developer liquid into the pump inlet conduit 25 of the first conduit 24 and thereby reduce the pressure within that portion of the first conduit 24. As the pressure is decreased, the replenishing liquid in the liquid container 68, which is at atmospheric pressure because of the vent 70, will be urged by the atmospheric pressure to flow through the second conduit means into the low-pressure portion of the first conduit means. The impedance means 74 in the second conduit means can be adjusted by experimentation so that when the float 52 is nearly seated, the impedance in the second conduit means will be overcome and the replenishing liquid will flow through the second conduit means from the container 68 into the first conduit means 24.

The replenishing liquid drawn into the first conduit means will be pumped through the pump discharge portion 27 of the first conduit means 24 and into the processing bin 10. When enough liquid has been drawn from the replenisher container 68 into the flow system, the level of the liquid in the processing bin 10 will rise to the proper height above the end 30 of the return conduit 14 to provide an adequate flow through the return conduit back to the reservoir 12 to raise the float from its seated position.

Thus, it is apparent from the above description that a dynamic equilibrium will soon be established in the flow system. The float 46 and reservoir 12 will automatically induce a low pressure within the pump inlet conduit means 25 between the reservoir and the pump 26 to induce a suflicient quantity of replenisher to enter the flow system to compensate for the developer liquid which is being consumed by the developing process.

It should be pointed out that the size of the float in the reservoir makes it almost impossible for the float to jam during normal operations of the system and therefore, the system is extremely reliable.

lt should also be pointed out that the suction created by the pump 26 in the first conduit means combined with the impedance means in the second conduit means prevents any flow of developer liquid from the flow system into the replenisher container and thereby prevents any contamination of the replenisher.

It should further be pointed out that this automatic replenishing apparatus does not require any delicate equipment or carefully machined items such as venturi tubes, or photoelectric cells.

It should also be noted that with the exception of the pump 26 there is but one moving part in the entire automatic replenishing system, therefore making the apparatus highly reliable.

It should further be noted that the replenishing system is extremely sensitive to the level or the quantity of developer liquid in the flow system. Therefore, a minimum of developer liquid is necessary for operating the developing system, since the replenishing liquid can be provided as soon as any small quantity of the developer liquid is consumed.

Although the float 46 is shown in the FIGURE as a spherical body it could have many other shapes and configurations and still function sufiiciently for proper operation of the invention. The exact diameter dimension of the float is also not a critical feature for the functioning of the invention. All that is necessary is that the diameter of the float be large enough to prevent the float from jamming in any position within the reservoir, and yet small enough to allow the float to freely sense the level of the liquid in the reservoir.

Although the impedance means in the second conduit means is shown in the FIGURE as a narrowed section of the second conduit, there are numerous other methods of providing the impedance. The impedance provided by the frictional coefficient of the material from which the conduit is fabricated could be used for the operation of the invention. In such cases, the impedance could be adjusted within practical limits by merely lengthening or shortening the length of the second conduit 60 to correspondingly increase or decrease the impedance means. In certain other circumstances it might be so desirable to adjust the impedance means by use of a clamping device located on the second conduit means.

It should also be pointed out that the end 44 of the first conduit means need not protrude above the bottom 40 of the reservoir means in order to obtain adequate valve function from the float 46. The conical portion 42 connecting the cylindrical section 38 with the circular bottom portion 40 of the reservoir provides a suitable seating surface for the float 46.

It will be understood that various changes in the details, materials, and arrangements of parts which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.

lclaim:

1. Apparatus for adding liquid to a liquid flow system comprising:

first conduit means in said system for carrying the liquid flowing in said system;

valve means serially connected with said first conduit means and responsive to the level of liquid at a point in said system to produce a pressure drop in said first conduit means upon actuation of said valve means;

container means holding a supply of liquid to be added to said flow system;

second conduit means connecting said container means with said first conduit means; the pressure drop in the first conduit means produced by actuation of said valve means causing liquid in said container means to flow through said second conduit means into said first conduit means.

2. The combination claimed in claim 1 wherein said valve means responsive to said level of liquid include float valve means.

3. The combination claimed in claim 2 wherein:

said first conduit means include reservoir means for holding at least a portion of the liquid flowing in said liquid flow system; and

said float valve means are located within said reservoir means for producing a pressure drop in said first conduit means when the level of liquid in said reservoir means falls to a predetermined point.

4. The combination claimed in claim 3 wherein:

said reservoir means include outlet means disposed at the bottom of said reservoir means; and

said float valve means comprise:

a float in said reservoir means;

a seating surface in said reservoir means, said float seating on said seating surface for restricting flow through said outlet means when the level of liquid in said reservoir falls to a predetermined level.

5. The combination claimed in claim 4 wherein:

said seating surface is formed from a tapered section disposed in the bottom of said reservoir means; and

said float is a spherical body having a diameter substantially larger than the outlet means in said reservoir and which seats in said tapered surface when said level of liquid in said reservoir falls to said predetermined level.

6. The combination claimed in claim 3 comprising impedance means serially connected with said second conduit 0 means for preventing flow through said second conduit means at times other than when said valve means are actuated.

7. The combination claimed in claim 6 wherein said impedance means include the frictional forces produced by the flow of the liquid through said second conduit means.

8. The combination claimed in claim 7 wherein said impedance means further comprise a constriction in second conduit means.

9. The combination claimed in claim 3 further comprising:

using means for receiving at least a portion of the liquid flowing in said first conduit means;

said first conduit means communicating with said using means;

return conduit means communicating said using means with said reservoir means for returning at least a portion of said liquid received by said using means to said reservoir means; and

means coupled with said first conduit means for causing the liquid in the first conduit means to flow to said using means.

10. The combination claimed in claim 9 wherein:

said means for causing liquid to flow in said first conduit means include pump means disposed in said first conduit means downstream of said reservoir means;

said reservoir means including outlet means disposed at the bottom of said reservoir means; and

said float valve means include:

a float in said reservoir means;

a seating surface in the bottom of said reservoir means for coacting with said float to restrict flow through said outlet means when the level of liquid in said reservoir falls to a predetermined level.

11. The combination claimed in claim 10 further comprising impedance means in said second conduit means for adjusting the pressure drop in said first conduit means necessary to induce flow in said second conduit means from said container means to said first conduit means.

12. In a developing system having a circulating liquid developer flowing through a processing bin, the apparatus for maintaining a uniform quantity of said developer comprising:

a reservoir for said developer liquid having an inlet and an outlet;

first conduit means connecting the outlet of said reservoir with said processing bin;

pump means disposed in said first conduit means to pump developer from said reservoir to said processing bin;

return conduit means connecting said processing bin to the inlet of said reservoir to return developer to said reservoir;

float valve means in said reservoir for restricting flow through said outlet of said reservoir when the level of developer in said reservoir falls to a predetermined level; said valve means comprising:

a spherical float in said reservoir, substantially filling the cross-sectional area of said reservoir;

7 8 a seating surface at the bottom of said reservoir for coactsaid reservoir and said pump means;

ing with said float to restrict flow through said outlet of impedance means in said second conduit means to adjust said reservoir and thereby create a pressure drop in the P p required in said first conduit means aid first d it means; to induce flow from said container means to said first a container f l i hi fl i conduit means, and to prevent flow from said first conduit means to said container means.

i i i i i a second conduit means connecting said container with said first conduit means at a point intermediate said outlet of 

1. Apparatus for adding liquid to a liquid flow system comprising: first conduit means in said system for carrying the liquid flowing in said system; valve means serially connected with said first conduit means and responsive to the level of liquid at a point in said system to produce a pressure droP in said first conduit means upon actuation of said valve means; container means holding a supply of liquid to be added to said flow system; second conduit means connecting said container means with said first conduit means; the pressure drop in the first conduit means produced by actuation of said valve means causing liquid in said container means to flow through said second conduit means into said first conduit means.
 2. The combination claimed in claim 1 wherein said valve means responsive to said level of liquid include float valve means.
 3. The combination claimed in claim 2 wherein: said first conduit means include reservoir means for holding at least a portion of the liquid flowing in said liquid flow system; and said float valve means are located within said reservoir means for producing a pressure drop in said first conduit means when the level of liquid in said reservoir means falls to a predetermined point.
 4. The combination claimed in claim 3 wherein: said reservoir means includes outlet means disposed at the bottom of said reservoir means; and said float valve means comprise: a float in said reservoir means; a seating surface in said reservoir means, said float seating on said seating surface for restricting flow through said outlet means when the level of liquid in said reservoir falls to a predetermined level.
 5. The combination claimed in claim 4 wherein: said seating surface is formed from a tapered section disposed in the bottom of said reservoir means; and said float is a spherical body having a diameter substantially larger than the outlet means in said reservoir and which seats in said tapered surface when said level of liquid in said reservoir falls to said predetermined level.
 6. The combination claimed in claim 3 comprising impedance means serially connected with said second conduit means for preventing flow through said second conduit means at times other than when said valve means are actuated.
 7. The combination claimed in claim 6 wherein said impedance means include the frictional forces produced by the flow of the liquid through said second conduit means.
 8. The combination claimed in claim 7 wherein said impedance means further comprise a constriction in said second conduit means.
 9. The combination claimed in claim 3 further comprising: using means for receiving at least a portion of the liquid flowing in said first conduit means; said first conduit means communicating with said using means; return conduit means communicating said using means with said reservoir means for returning at least a portion of said liquid received by said using means to said reservoir means; and means coupled with said first conduit means for causing the liquid in the first conduit means to flow to said using means.
 10. The combination claimed in claim 9 wherein: said means for causing liquid to flow in said first conduit means include pump means disposed in said first conduit means downstream of said reservoir means; said reservoir means including outlet means disposed at the bottom of said reservoir means; and said float valve means include: a float in said reservoir means; a seating surface in the bottom of said reservoir means for coacting with said float to restrict flow through said outlet means when the level of liquid in said reservoir falls to a predetermined level.
 11. The combination claimed in claim 10 further comprising impedance means in said second conduit means for adjusting the pressure drop in said first conduit means necessary to induce flow in said second conduit means from said container means to said first conduit means.
 12. In a developing system having a circulating liquid developer flowing through a processing bin, the apparatus for maintaining a uniform quantity of said developer comprising: a reservoir for said developer liquid having an inlet and an outlet; first conduit means connecting the outlet of sAid reservoir with said processing bin; pump means disposed in said first conduit means to pump developer from said reservoir to said processing bin; return conduit means connecting said processing bin to the inlet of said reservoir to return developer to said reservoir; float valve means in said reservoir for restricting flow through said outlet of said reservoir when the level of developer in said reservoir falls to a predetermined level; said valve means comprising: a spherical float in said reservoir, substantially filling the cross-sectional area of said reservoir; a seating surface at the bottom of said reservoir for coacting with said float to restrict flow through said outlet of said reservoir and thereby create a pressure drop in said first conduit means; a container of replenishing fluid; a second conduit means connecting said container with said first conduit means at a point intermediate said outlet of said reservoir and said pump means; impedance means in said second conduit means to adjust the pressure drop required in said first conduit means to induce flow from said container means to said first conduit means, and to prevent flow from said first conduit means to said container means. 